An effective oral composition can maintain and preserve tooth appearance by removing dental stains and polishing the teeth. It may clean and remove external debris as well, which can aid the prevention of tooth decay and promote gingival health.
Abrasives in oral compositions aid in the removal of the tightly adherent pellicle film to which dental stains affix. Pellicle film usually comprises a thin acellular, glycoprotein-mucoprotein coating, which adheres to the enamel within minutes after teeth are cleaned. The presence of various food pigments lodged within the film accounts for most instances of teeth discoloration. An abrasive may remove the pellicle film with minimal abrasive damage to oral tissue, such as the dentin and enamel.
In addition to cleaning, it may be desirable for abrasive systems to provide polishing of tooth surfaces, as polished surfaces may be more resistant to ectopic deposition of undesirable components. Tooth appearance may be improved by imparting a polished character to the teeth, because the surface roughness, that is, its polish, affects light reflectance and scattering, which integrally relate to the teeth's visual appearance. The surface roughness also affects tooth feel. For example, polished teeth have a clean, smooth, and slick feel.
Numerous dentifrice compositions use precipitated silicas as abrasives. Precipitated silicas are noted and described in U.S. Pat. No. 4,340,583, Jul. 20, 1982, to Wason, EP Patent 535,943A1, Apr. 7, 1993, to McKeown et al., PCT Application WO 92/02454, Feb. 20, 1992 to McKeown et al., U.S. Pat. No. 5,603,920, Feb. 18, 1997, and U.S. Pat. No. 5,716,601, Feb. 10, 1998, both to Rice, and U.S. Pat. No. 6,740,311, May 25, 2004 to White et al.
While providing effective cleaning of teeth, precipitated silicas in oral care compositions may present compatibility problems with key formula actives, such as oxidizing agents like peroxide. Peroxides have been proven effective for oral cosmetic purposes, such as tooth whitening, as well as for the treatment of gingivitis, sensitivity, oral lesions, erosion, cavities, calculus, periodontitis, herpetic stomatitis, plaque, and for relieving bad breath. But often, due to compatibility problems, peroxide and other oxidizing agents are not effectively delivered to the user. These compatibility problems have been shown to be directly related to surface properties of precipitated silicas such as surface area, number of hydroxyl groups, and porosity, and to the purity of the silica.
A need exists for an abrasive system that has good compatibility with oral care actives, such as oxidizing agents, while providing effective and safe cleaning and polishing of dental tissue. The compositions of the present invention may provide such benefits. The present invention therefore relates to oral compositions comprising fused silica and an oxidizing agent.